Field of the Invention
The present invention relates to an electrophotographic member to be used in an electrophotographic apparatus, and a process cartridge and an electrophotographic apparatus each including the electrophotographic member.
Description of the Related Art
In an electrophotographic apparatus (a copying machine, facsimile, or printer employing an electrophotographic system), an image is formed through the following process. First, an electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”) is charged by a charging member and then exposed by a laser, to thereby form an electrostatic latent image on the photosensitive member. Next, toner in a developer container is applied onto a developing roller by a toner feed roller and a developing blade. The electrostatic latent image on the photosensitive member is developed with the toner conveyed to a developing region by the developing roller at a portion in which the photosensitive member and the developing roller are in contact with, or close to, each other. After that, the toner on the photosensitive member is transferred onto recording paper by a transfer unit, and is fixed by heat and pressure to form an image. The toner remaining on the photosensitive member is removed by a cleaning blade.
In the electrophotographic apparatus, an electrophotographic member including an electroconductive layer is used as each of the developing roller, the charging member, the toner feed roller, the cleaning blade, and the developing blade. The electrophotographic member needs to have its electrical resistance value controlled to the range of from 105Ω to 109Ω without dependence on its use conditions and use environment. As an electroconductive agent to be added to the electroconductive layer to adjust electroconductivity of the electrophotographic member, there is known an ionic electroconductive agent typified by a quaternary ammonium salt compound. The ionic electroconductive agent has the following advantage as compared to the case of using, as the electroconductive agent, an electronic electroconductive agent like carbon black: by virtue of high dispersibility of the electroconductive agent, unevenness in electrical resistance value hardly occurs. Meanwhile, the ionic electroconductive agent has the following property: its electroconductivity is liable to fluctuate depending on an environment, and for example, the electroconductivity decreases under a low-temperature and low-humidity environment. Accordingly, the ionic electroconductive agent has had a problem in that the electrophotographic member cannot achieve a desired resistance value in some cases under the low-temperature and low-humidity environment.
As an approach to solving such problem, in Japanese Patent Application Laid-Open No. 2004-331885, there is a disclosure of a method involving using, as the electroconductive agent, an ionic liquid having a specific structure. In addition, in Japanese Patent Application Laid-Open No. 2011-118113, there is a disclosure of an electroconductive roller including a urethane coat layer obtained by curing a urethane resin composition containing a specific amount of an ionic liquid having two hydroxy groups.
In recent years, the electrophotographic apparatus has been required to be capable of maintaining high image quality and high durability even under a more severe environment.
One aspect of the present invention is directed to providing an electrophotographic member which hardly undergoes deformation even when subjected to a load over a long period of time under a high-temperature and high-humidity environment and thus can stably form a high-quality electrophotographic image.
Another aspect of the present invention is directed to providing an electrophotographic apparatus which can stably output a high-quality electrophotographic image and a process cartridge to be used in the apparatus.